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Optical properties of the iron-based superconductor LiFeAs single crystal

Optical properties of the iron-based superconductor LiFeAs single crystal
Min, Byeong HunHong, Jong BeomYun, Jae HyunIizuka, TakuyaKimura, Shin-ichiBang, YunkyuKwon, Yong Seung
DGIST Authors
Kwon, Yong Seung
Issued Date
Article Type
Dielectric FunctionsHigh Temperature SuperconductorsInter-Band TransitionIron-Based SuperconductorsLow-Temperature DataMetallic BehaviorsOptical ConductivityOptical Conductivity SpectraPlasma FrequenciesReflectivity SpectraSemiconductor Quantum WellsSingle CrystalsSuperconductivity
We have measured the reflectivity spectra of the LiFeAs (Tc = 17.6 K) single crystal in the temperature range from 4 to 300 K. In the superconducting (SC) state (T < Tc), the clean opening of the optical absorption gap was observed below 25 cm-1, indicating an isotropic full gap formation. In the normal state (T > Tc), the optical conductivity spectra display typical metallic behavior with the Drude-type spectra at low frequencies, but we found that the introduction of the two Drude components best fits the data, indicating the multiband nature of this compound. A theoretical analysis of the low-temperature data (T = 4 K < Tc) also suggests that two SC gaps best fit the data and their values were estimated as Δ1 = 3.3 meV and Δ2 = 1.59 meV, respectively. Using the Ferrell-Glover-Tinkham sum rule and dielectric function 1 (ω), the plasma frequency of the SC condensate (ωps) is consistently estimated to be 6665 cm-1, implying that about 65% of the free carriers of the normal state condense into the SC condensate. To investigate the various interband transition processes (for ω > 200 cm-1), we have also performed the local-density approximation band calculation and calculated the optical spectra of the interband transitions. This theoretical result provided qualitative agreement with the experimental data below 4000 cm-1 . © IOP Publishing and Deutsche Physikalische Gesellschaft.
Institute of Physics Publishing
Related Researcher
  • 권용성 Kwon, Yong Seung 화학물리학과
  • Research Interests High Tc Superconductors and magnetic materials; Thermoelectric Materials
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Department of Physics and Chemistry Quantum Functional Materials Laboratory 1. Journal Articles


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